1. Field of the Invention
The present invention relates to a rice grain-like low-calorie food having glucomannan, a type of thickening polysaccharide, as the base thereof, and particularly it relates to a substance which is suitable to be mixed with rice and cooked to prepare a food.
Unless otherwise specified, the use of "part" and "%" in expressing the composition units in the following explanation refers to weight units.
2. Description of the Prior Art
Konjak gel, which is a food prepared using as a raw material glucomannan obtained from konjak tuber and the like, contains a poorly digestible polysaccharide as a main ingredient, and thus it has received attention not only as a weight-prevention diet food (low-calorie food), but also as a food with a prophylactic effect against adult diseases and a promoting effect for defecation.
Konjak gel is mostly used for the preparation of cooked foods and sauce-topped dishes by cutting flat konjak or stringy konjak into an appropriate size. Recently, the use of stringy konjak as a diet food for overweight people has been proposed, by cutting it finely, and mixing and cooking it with rice, for a reduction in the amount of intake of rice and decrease in calories. (See "Hanayo Sumi's Low-Calorie Cooking", Esse separate volume, issued by Fuji Television publication, p.44).
Nevertheless, it is somewhat bothersome to cut stringy konjak into small rice-size bits using a kitchen knife, and thus it would be convenient to have in a rice grain-like form konjak. Furthermore, a rice grain-like low-calorie food (hereunder referred to as "rice grain-like food") using a konjak ingredient (glucomannan) as the base and resembling rice grains in its appearance and texture, would facilitate a greater intake of the konjak ingredient, and would thus be desirable.
One such example of a rice grain-like food which has been proposed is a rice grain-like low-calorie food prepared by an aqueous dispersion gelating in an alkali solution of a mixture comprising added starch, cellulose (dietary cellulose) and pregelantinized starch, added to konjak paste (see Japanese Patent Application Publication HEI 5- 53461).
However, the amount of added starch in this rice grain-like low-calorie food is as high as 4-13 parts per part of refined konjak flour (see column 5, lines 15-16 of the above mentioned Patent Application Publication), and therefore although its calorie content is considerably lower than that of normal rice, when it is mixed and cooked with rice its calorie contribution cannot be ignored, and thus it is may hardly be said to be a diet food. Incidentally, in an Example in the above mentioned Patent Application Publication, it is mentioned that the per 100 gram calorie content of the rice is about 150 kcal, while that of the rice grain-like food is 33 kcal (see column 7, line 15 - column 8, line 3).
Here, reduction of the amount of added starch has been considered, but it is assumed that this will cause the above mentioned rice grain-like low-calorie food to have insufficient freeze resistance, and also to have an appearance and texture closer to that konjak gel, thus losing the appearance and texture of rice grains.
The above mentioned rice grain-like food is desired to have excellent freeze resistance, from the point of view of distribution and preservation of the food, etc., but a reduction in the amount of added starch, which acts also as a freeze resistant agent, means that the relative glucomannan content becomes higher, which leads to denaturation upon freezing, as in the case of konjak, etc., causing an irreversible loss of the form and appearance as compared to that prior to freezing, and thus it becomes unsuitable for use as a food material. It is stated in the Claims and elsewhere in Japanese Patent Laid-Open Publication No. SHO 62-175149 that, to achieve freeze resistance, it is necessary to incorporate starch at a proportion of 3-7 parts per part of refined konjak flour (glucomannan).
Also, the rice grain-like low-calorie food according to the above mentioned Patent Application Publication has had, when mixed and cooked with rice, a specific gravity approaching that of water, and a layer of this rice grain-like material has tended to separate from the rice and to accumulate on the surface, making it difficult to mix and cook the ingredients to prepare a uniform food product.